The present invention relates to a process and a device for the production of a composite part by means of the sequential introduction of several fillings (consisting of at least one free-flowing reaction mixture, of which at least one forms a foamed material) into the hollow space of the mold of a closed form tool. A mixing device is attached to the form tool. The mixer comprises injector nozzles for the reaction components pointing into a mixing chamber and an ejector piston for the cleaning of the mixer chamber. The ejector piston may be slid forward right up to the outlet orifice of the mixing chamber.
There is often a need for composite parts which consist of several layers, e.g., a foamed material core with an elastic, unfoamed, surface layer. Such parts find applications, for example, in motor vehicles in the form of "soft faces", bumpers or in the form of side aprons. In many cases a material having a covering on only one side would be sufficient; however it has been shown in practice that the composite deforms when very different materials are used.
According to DE-A-2,127,582 (corresponding to US-A 3,954,926) it is known to use a single mixing device with reaction mixtures that differ only in the amount of blowing agent. It is also known from this reference to use at least two mixing devices, with which various reaction mixtures are introduced one after the other. In the process, one mixing device is associated with each side of the hollow space of the mold, so that two feeder openings are present. The expense due to the mixing devices, of which there are at least two, is considerable.
The object of the present invention consists in providing a device and a process for the manufacture of composite parts wherein one mixing device is sufficient.